Kansas City Chiefs wide receiver Rashee Rice is out for at least the next four weeks and potentially longer after sustaining a bad-looking knee injury in Sunday’s game against the Los Angeles Chargers.

The injury occurred on an interception thrown by Patrick Mahomes. As Chargers cornerback Kristian Fulton ran the ball back, Rice caught him from behind and stripped the ball. At the same time, Mahomes went for a low tackle in front of Fulton, with his right shoulder hitting Rice’s right knee instead.

Replay showed Rice’s knee bending the wrong way.

Rice had to be carted off the field and was reportedly feared to have torn his ACL, a season-ending injury. Four days later, the nature of the injury remains unclear, but the Chiefs placed him on injured reserve Thursday, which will keep him off the field for at least the next four weeks.

Also on Thursday, Mahomes discussed the fateful play and, predictably, didn’t feel good about his role in the injury to his WR1:

Through four games, Rice leads the Chiefs in receptions with 24 and receiving yards with 288. He was on pace for a strong follow-up to a promising rookie year, despite some offseason issues such as his dangerous street racing accident, but his status for the rest of the season is now unclear.

With Rice out, more of the receiving responsibility will fall on tight end Travis Kelce and rookie wideout Xavier Worthy as the Chiefs go for a three-peat.